Transformer Cooling

In transformers, the loss of energy due to core losses and copper losses are converted into heat energy. This results in the temperature rise of the winding and other parts. So it is necessary to provide coolong arrangements in transformers. Normally the transformers are cooled in any one of the following methods.

Air Natural Cooling

Air Natural method is used for cooling dry type transformers having low capacity at low voltage. Here, the natural air in the surroundings of the transformer tank is used to cool the transformer.

Air Blast Cooling

Air Blast cooling methods is also used for dry type transformers. The core and winding of the transformers are cooled by forced circulation of air. Air blast of cooling is used in the transformers having voltage upto 25kv. Usually the transformers are placed over an air chamber in which the airis maintained under pressure by blowers. The air is forced through core and windings and is discharged through the upper body of cooling construction. The dust particles in the air are filtered before it enters into the transformer.

Oil Immersed Natural Cooling

In oil immersed natural cooling, the assembly of core and coils are immersed in the insulating oil container in an iron tank. The heat produced in the core and windings is conducted by the circulation of oil to the surface which dissipates it to the surroundings. In larger rating transforemers, the dissipating surface is increased by providing large number of tubes on its sides. The oil not only keeps the windings cool, but also provides the transformers with additional insulation. Hence oil immersed natural cooling transformers are used for distribution purpose.

Oil Immersed Forced Air Cooling

In oil immersed forced air cooling, the core and windings are immersed in oil and cooling is increased by forced air over the cooling surfaces. The air is forced over external surfaces such as radiators and case tubes. The air is forced by means of fan mounted external to the transformer.

Oil Immersed Water Cooling

In oil immersed water cooling, the core and winding are immersed in oil and cooling is increased by circulation of cold water through the tubes around the transformer tank.

Oil Forced Natural Cooling

In oil forced natural cooling, a cooling oil is forced to circulate through core and windings of the oil immersed transformer. In oil forced natural cooling, a seperate cooler is mounted away from the transformer tank . thecooler is connected to the transformer tank with two pipes one at the top and the other at the bottom. The oil is circulated by pump from the top of the transformer tank to the cooler. The cold oil from the cooler isreturned to the transformer tank by bottom pipe.